Composition of matter

ABSTRACT

There is disclosed a fugitive vehicle system comprising at least two organic components, at least one component being a solid polymeric material capable of pyrolyzing in a non-oxygen containing environment and at least one other component being a solvent for the solid polymeric material, the solvent being capable of removal at a temperature below the pyrolyzing temperature of the polymeric material. This fugitive vehicle system is especially suitable in microelectronic applications.

This is a continuation of copending U.S. patent application Ser. No.302,062 filed Oct. 30, 1972 (now abandoned) which in turn is a divisionof copending U.S. patent application Ser. No. 174,197 filed Aug. 23,1971 (now U.S. Pat. No. 4,014,845).

THE DISCLOSURE

This invention relates to a novel fugitive vehicle system comprising asolid polymeric material and a solvent.

Fugitive vehicle systems are generally well known in the prior art, asevidenced for example by U.S. Pat. No. 2,312,229 issued to Andersonwhich discloses a process for coating vitreous surfaces with fluorescentmaterials by suspending fluorescent powder in a binder comprising asolution of polystyrene in a solvent. Similar systems are disclosed byU.S. Pat. No. 2,328,101 issued to Rosenblatt and U.S. Pat. No. 3,475,161issued to Ramirez.

Fugitive vehicle systems have been especially useful in the coating art.Thus, particulate coating materials are commonly applied to substratesby a wet process, that is, while dispersed in a system consisting of abinder and a solvent. Such a process typically requires mixing of abinder, a solvent, and an inorganic material to form a paste or slurrywhich is applied to the surface to be coated.

The wet coating technique is commonly used to seal glass or ceramicparts, as in the formation of cathode ray tubes wherein the face plateis attached to the funnel. In this technique, a paste having solderglass distributed througout a binder-solvent system is applied to theedges of one part in the form of a ribbon. The remaining part is thenplaced in contact with the paste and the assemblage is heated toevaporate the solvent, burn out the binder, and fuse the solder glass.While this technique is extensively used, quality control is difficultand expensive because of carbonaceous or like residue which may not beremoved by evaporation or burning during the heating step. Likewise,during the evaporation of the solvent, there may be changes in theviscosity and/or thixotropic character of the system which may result insuch deleterious effects as orange peel formation, fish eye formation,etc., especially on flat surfaces.

In an effort to overcome the difficulties inherent in applying a coatingor sealant to substrates via a binder-solvent system, the prior art hasused dry coating compositions containing polymeric binders and havingthe particulate coating material uniformly distributed therethrough.These compositions are formed into films which are applied to thesubstrate to be coated and then heated to burn out the binder and form acoating of the inorganic material usually in fused or sintered form.However, the presence of carbonaceous residue may still present aproblem in such a system.

In copending U.S. patent application Ser. No. 825,410, filed May 16,1969 by Fred E. Mansur and copending U.S. patent application Ser. No.806,320, filed Mar. 11, 1969 by Don N. Gray and John D. Grier, bothapplications being assigned to the same assignee as the instantapplication, there are disclosed novel wet coating systems comprisingliquid poly (alpha substituted) styrene dispersed in a cyclic isoprenoidsolvent.

In accordance with the practice of this invention, there is provided afugitive vehicle system comprising at least two organic components, atleast one component being a solid polymeric material capable ofpyrolyzing in a non-oxygen containing environment and at least one othercomponent being a solvent for the polymeric material, the solvent beingcapable of removal at a temperature below the pyrolyzing temperature ofthe polymeric material.

As used herein, "pyrolyzing" is defined as the decomposition of thepolymeric material to gaseous products without passing through a broadliquid range and without leaving a noticeable carbonaceous or other likeresidue which would interfere with the intended function of the system.

The polymeric material is one which will pyrolyze, as distinguished fromvaporization, when appropriate energy is applied thereto at somepredetermined energy level about the level of energy required to removethe solvent.

Energy level, as used herein, is intended to include any reasonablymeasurable molecular energy state which is related to the pyrolyzing ofthe polymer and/or removal of the solvent. The most obvious energy levelis temperature, which has been defined as the average molecular kineticenergy. Hereinafter, temperature level will be used as a synonym forenergy level. However, the invention is not limited to temperature levelalone, but is intended to include any molecular energy level or statewhich can be obtained by any appropriate energy from any source ormeans, such as chemical, electrical, thermal, mechanical, sonic, etc.Likewise, the energy can be transmitted in any suitable form such as byelectromagnetic radiation, visible or invisible, e.g., infra-red,ultraviolet, x-rays, gamma rays, and beta rays.

The polymeric material, when solvent-free, is solid under the conditionsof handling, e.g., typically room or factory temperatures ranging fromabout 40° F. to about 120° F. However, more extreme temperatures arecontemplates if the conditions of handling so warrant.

The use of a solid polymeric material is advantageous in that thematerial behaves as a binder during the interval between the evaporationof the solvent and the pyrolytic removal of the polymeric material. Thismay be especially important when the fugitive vehicle system is beingloaded with other materials, e.g., for coating a substrate.

The polymeric material is typically selected from one or morepyrolyzable solid polymers or copolymers such as polyethers includingpoly (tetrahydrofuran), poly (1,3-dioxolane), and poly (alkyleneoxides), especially poly (ethylene oxide) or poly (propylene oxide);poly (alkyl methacrylates) including those where the alkyl contains oneto six carbons, especially poly (methyl methacrylate), poly (ethylmethacrylate), and poly (n-butyl methacrylate); methacrylate copolymersincluding methyl methacrylate/n-butyl methacrylate copolymers, methylmethacrylate/alpha methyl styrene copolymers, n-butyl methacrylate/alphamethyl styrene copolymers, methyl methacrylate/styrene copolymers,methyl methacrylate/dimethyl itaconate copolymers; and other selectedpolymers and copolymers including polyisobutylene; poly (trimethylenecarbonate); poly (beta-propiolactone); poly (deltavalerolacetone); poly(ethylene carbonate); poly (propylene carbonate); poly (ethyleneoxalate); vinyl toluene/alpha-methylstyrene copolymers;styrene/alpha-methylstyrene copolymers; and olefin-sulfur dioxidecopolymers.

In one specific embodiment hereof, there is used a polymeric materialhaving oxygen atoms selectively incorporated in its molecular chain, as,for example, peroxy linkages in the chain. Such a pyrolyzable polymer isdisclosed in copending U.S. patent application Ser. No. 653,020, filedJuly 13, 1967 by Dr. Don N. Gray and assigned to the same assignee asthat of the instant patent application. Typically there is used acopolymer, terpolymer, or quadpolymer of oxygen and at least one monomerof alkyl methacrylate with the alkyl containing one to six carbon atoms,e.g., methyl to hexyl, preferably butyl. Copolymers of oxygen with othervinyl monomers may also be utilized.

The common characteristics of the selected polymeric material is that itmust be solid at ambient temperature and pyrolyzable at an elevatedtemperature, e.g., about 250° C. to about 450° C.

This pyrolysis mechanism of removal of the composition of the inventionis of great advantage in non-oxygen-containing atmospheres, but thecompositions may also be used in an oxygen-containing atmosphere. Thischaracteristic permits the use of a continuum of atmospheric pressuresdownward from somewhat less than 14.7 lbs. per sq. absolute to vacuaapproaching the micron range. Likewise, inert environments such asnitrogen, argon, etc. may be used.

The organic solvent component of the vehicle system comprises one ormore organic solvents having a boiling temperature below the pyrolysistemperature of the polymer, e.g., within a range of about 100° C. toabout 400° C., preferably about 200° C. to about 350° C. The use of highboiling solvents makes the fugitive system effectively non-drying atroom temperature.

Examples of suitable solvents include polychlorinated polyphenyls(Arochlor 1221 or 1232, manufactured by Monsanto Chemical Co.,); dialkylphthalates, such as dimethyl, diethyl, or di-n-butyl phthalate;di-n-butyl succinate; dimethyl sebacate, dibenzyl ether; butyl benzoate;acetyl triethyl citrate; glyceryl triacetate; beta-ethoxy ethylbenzoate; isoamyl benzoate; benzyl benzoate; isobutyl salicylate;isoamyl salicylate; benzyl salicylate; ethyl laurate; butyl oleate;ethyl myristate; butyl benzyl phthalate; dimethyl suberate; diethylsebacate; diethyl azelate; di-n-butyl adipate; diisobutyl adipate;dibutyl sebacate; dibutyl tartrate; glyceryl tributyrate; diethylisophthalate; butyl palmitate; dodecylbenzene; tetradecylbenzene;pentaethylbenzene; diphenylmethane; 1,1-diphenylethane;1-choronaphthalene; 1-bromonaphthalene; dimethyl-naphthalene (variousisomers, and mixtures thereof) 1-methoxy naphthalene; n-alkanescontaining 14 to 20 carbon atoms and mixtures thereof; diphenyl ether;bis(alpha-methylbenzyl) ether; tetraethylene glycol dimethyl ether;2-benzyloxyethanol; phenyl n-hexyl carbinol; triethylene glycol;1,4-pentanediol, hexanophenone; 1-naphthyl methyl ketone;p-n-pentylphenol; N-cyclohexyl-2-pyrrolidone; glutaronitrile; andp-methyoxyphenylacetonitrile. The selected solvent may also be thermallydegradable to volatile products, e.g., within the boiling rangetemperatures indicated above.

Among the organic solvents, it is also possible to select some which actas plasticizers for the polymer, thereby obtaining a beneficialsolvating effect.

The relative proportions of solvent (or plasticizer) and polymericmaterial will depend upon the respective types of materials. However,the weight ratio of solvent to polymeric material will generally bewithin a range of about 100:1 to about 1:100, preferably about 10:1 toabout 1:10.

The fugitive vehicle composition of this invention has numerousadvantages and utility depending upon what additional ingredients, ifany, are incorporated therein. Such additional ingredients include notby way of limitation both liquid and solid substances such as pigments,fillers, resins, ceramics, glasses, etc.

The composition is especially advantageous in the formation ofthick-film systems designed for processing in non-oxidizing atmospheres,e.g., as in the preparation of microelectronic circuits, devices, andcomponents thereof. Another particular use comprises a glazing processwherein a powdered glass is applied to a substrate and subsequentlymelted to form a continuous film, e.g., such as a dielectric film in agas discharge display/memory device.

We claim:
 1. As a composition of matter a particulate inorganic materialdispersed in a fugitive vehicle system, said particulate material havinga fusion temperature and said fugitive vehicle system comprising atleast two organic components, at least one component being a polymericmaterial which is a solid at ambient temperature, has a pyrolysistemperature of about 250° C. to about 450° C. and below said fusiontemperature of said particulate material and following pyrolysis in anon-oxygen containing environment, leaves no carbonaceous residue havinga deleterious effect on said particulate material, said polymericmaterial having oxygen atoms selectively incorporated in its molecularchain and being at least one pyrolyzable solid polymer or copolymerselected from the group consisting of polyethers, copolymers andterpolymers and quadpolymers of oxygen and at least one monomer of alkylmethacrylate, poly (trimethylene carbonate), poly(beta-propiolactone),poly(delta-valerolactone), poly(ethylene carbonate), poly(propylenecarbonate), and poly(ethylene oxalate), and at least one other componentbeing a solvent for dissolving said polymeric material, said solventbeing a liquid at ambient temperature and having a volatilization ordecomposition temperature range of about 200° C. to about 350° C., butbelow the pyrolysis temperature of said polymeric material.
 2. Thecomposition of claim 1 wherein said solvent is selected from the groupconsisting of polychlorinated polyphenyls, dialkyl phthalates,di-n-butyl succinate, dimethyl sebacate, dibenzyl ether, butyl benzoate,acetyl triethyl citrate, glyceryl triacetate, beta-ethoxy ethylbenzoate, isoamyl benzoate, benzyl benzoate, isobutyl salicylate,isoamyl salicylate, benzyl salicylate, ethyl laurate, butyl oleate,ethyl myristate, butyl benzyl phthalate, dimethyl suberate, diethylsebacate, diethyl azalate, di-n-butyl adipate, diisobutyl adipate,dibutyl sebacate, dibutyl, tartrate, glyceryl tributyrate, diethylisophthalate, butyl palmitate, dodecylbenzene, tetradecylbenzenepentaethylbenzene, diphenylmethane, 1,1-diphenylethane,1-chloronaphthalene, 1-bromonaphthalene, dimethylnaphthalene, 1-methoxynaphthalene, n-alkanes containing 14 to 20 carbon atoms, diphenyl ether,bis(alpha-methylbenzyl)ether, tetraethylene glycol dimethyl ether,2-benzyloxyethanol, phenyl n-hexyl carbinol, triethylene glycol,1,4-pentanediol, hexanophenone, 1-naphthyl methyl ketone,p-n-pentylphenol, N-cyclohexyl-2-pyrrolidone, glutaronitrile, andp-methoxyphenylacetonitrile.
 3. The composition of claim 2 wherein saiddialkyl phthalates are selected from the group consisting of dimethyldi-n-butyl phthalate and diethyl di-n-butyl phthalate.
 4. Thecomposition of claim 1 wherein said particulate inorganic material is aglass.
 5. As a composition of matter a particulate inorganic materialdispersed in a fugitive vehicle system, said particulate material havinga fusion temperature and said fugitive vehicle system comprising atleast two organic components, at least one component being a polymericmaterial which is a solid at ambient temperature, has a pyrolysistemperature of about 250° C. to about 450° C. and below said fusiontemperature of said particulate material and following pyrolysis in anon-oxygen containing environment, leaves no carbonaceous residue havinga deleterious effect on said particulate material, said polymericmaterial being a copolymer, terpolymer, or quadpolymer of oxygen and atleast one monomer of alkyl methacrylate with the alkyl containing one tosix carbon atoms, and at least one other component being a solvent fordissolving said polymeric material, said solvent being a liquid atambient temperature and having a volatilization or decompositiontemperature range of about 200° C. to about 350° C., but below thepyrolysis temperature of said polymeric material.
 6. The composition ofclaim 5 wherein the alkyl is n-butyl.
 7. The composition of claim 1wherein the weight ratio of solvent to polymeric material ranges fromabout 100:1 to about 1:100.
 8. The composition of claim 1 wherein saidparticulate material is a powdered material.
 9. The composition of claim5 wherein the alkyl is methyl.